The present invention relates to an abrasive-supporting head for honing machines.
As is known, the abrasive-supporting heads of machines for honing hard materials, such as granite and the like, have a supporting assembly for a plurality of abrasives which rotates about a vertical axis substantially perpendicular to the plane of arrangement of the slabs to be worked.
The abrasives used in such machines, due to well-known functional technical reasons, during their rotation about the above-said vertical axis together with the supporting assembly, also undergo an oscillation respectively about axes arranged radially with respect to the vertical axis.
In order to obtain the oscillation of the abrasive-supporting elements, a cam is commonly used which is adapted for controlling, according to a specific profile thereof, the raising and lowering of one or more idly mounted small wheels, biased by the action of a return spring, each of which is generally associated with an arm rigidly associated with the supporting pivot of the abrasive-supporting element.
The use of springs in the honing heads of honing machines implies the fact that the latter are negatively affected by the harmful effects of dust produced during the operation of the machine, and by the fact that the springs, after relatively short periods of time, lose elasticity, no longer ensuring a perfect contact between the small wheel and the profile of the cam, and furthermore, in some cases, the springs are subject to fatigue breakage and therefore require replacement, which implies the halting of the machine which an adverse effect on production costs.
Moreover, as can be easily deduced, the springs give rise to a variable load on the small wheel in contact with the profile of the cam which causes rapid wear both of said wheel, which must therefore undergo replacement, and of the profile of the cam, which is irreparably damaged.
Not least disadvantage of known honing machines is that the work surface of the profile of the cam is unchanged along its entire extension so that each one of said small wheels, besides rolling on the cam, also performs harmful slippage which gives rise to greater wear and a greater work effort.
With the aim of eliminating at least partially these disadvantages, by eliminating springs, a grinding wheel head has been provided, described in German Pat. No. 3408443, wherein the control device which, during the rotary motion of the grinding wheel head, moves the sectorial grinding wheels in continuous rotary motion, is essentially composed of a disk arranged inclined towards the horizontal work surface of the grinding wheel head.
The possibility of oscillating motion of the pivots between the jaws which project outwards from the inclined disk is to be ascribed to an articulated joint fixed on said pivots.
This articulated joint thus allows the relative motion in the jaws provided on the disk.
The rotary motion of said disk, together with the middle shaft, produces an oscillating motion of each sectorial grinding wheel also between two preset angles, related to a vertical surface which passes through the axis of the pivots.
This type of grinding wheel head, though it solves the problems related to the use of springs, has an imperfect geometry, which gives rise to the wear of the components anyway, and furthermore, due to its particular structure, gives rise to the simultaneous oscillation in the same direction of two diametrally opposite abrasive-supporting elements, generating an imbalance in the rotating masses during operation, with the consequent possible generation of vibrations which cause imperfections in the finished product.